1. Field of the Invention
The present invention relates to a liquid crystal display device.
2. Description of the Related Art
In the related art, liquid crystal display devices include a TFT substrate in which thin-film transistors (TFT) for driving liquid crystals are formed and a color filter substrate in which color filters are formed, and liquid crystals are interposed between the two substrates. In such liquid crystal display devices, a driving mode where images are displayed by applying a transverse electric field to the liquid crystals is referred to as an In-Plane Switching (IPS) mode or a transverse electric field driving mode. Such display devices are known to have a wide viewing angle performance.
JP 2009-168878 A discloses a liquid crystal display device in which metal wirings are electrically connected to a common electrode made from ITO (Indium Tin Oxide). Since ITO has a high resistance, the potentials of the common electrode can be made uniform by connecting the metal wirings having a low resistance to the common electrode.
Moreover, it is also known that even when a transparent common electrode is connected to the metal wirings so as to reduce resistance in order to reduce power consumption by increasing the aperture ratio of the liquid crystal display device, the number of metal wirings may be reduced according to need rather than forming the metal wirings over all the pixels.
Since it is difficult to form the metal wirings only in regions such as a black matrix and a transistor which naturally cannot transmit light therethrough, the metal wirings should be formed so as to pass a pixel region. Thus, the formed metal wirings decrease the aperture ratio, and accordingly, luminance decreases. However, it is desirable to suppress the decrease in luminance as much as possible.